Gameboy Development Forum
Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
(Launched in 2008)
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#1 2022-07-16 07:39:40
- Moex
- New member
- Registered: 2022-07-11
- Posts: 3
Flashcard based on HUC1a using flash memory adapter
Hello everyone 
currently I am planning to build a flash card based on a pcb from the Japanese Pokemon Card GB (DMG-TFDN). I am planning to solder a flash chip to it using the following flash memory adapter:https://www.jrodrigo.net/wiki/how-to-diy-a-gameboy-flash-cartridge-with-a-rom-adapter-board/.
According to the documentation of the adapter, it is compatible with the following cartridges in any case:
• DMG-A02-01: MBC5 + ROM (256/512/1024 KB) + RAM (32KB) + Battery
• DMG-A06-01: MBC5 + ROM (256/512/1024 KB) + RAM (8KB) + Battery
• DMG-A07-01: MBC5 + ROM (256/512/1024 KB)
• DMG-KFDN-10: MBC3 + ROM (256/512/1024 KB) + RAM (32KB) + Battery + Timer
• DMG-KFDN-01: MBC3 + ROM (256/512/1024 KB) + RAM (32KB) + Battery
• DMG-KECN-SP: MBC3 + ROM (256/512/1024 KB) + RAM (8KB) + Battery + Timer
• DMG-A40-01: PCB Photo – MBC7 + ROM (256/512/1024 KB) + RAM (512B) + Tilt
So my question is, is this technically even possible using this adapter?
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#2 2022-07-18 18:14:34
- Tauwasser
- Member
- Registered: 2010-10-23
- Posts: 160
Re: Flashcard based on HUC1a using flash memory adapter
Hi Moex,
welcome to the Gameboy Development Forum!
It is possible to use DMG-TFDN with the adapter by JRodrigo. The pinout matches exactly—it's a standard footprint
However, you will be limited to 1 MiB of ROM, because the HuC1 on DMG-TFDN only has six upper address lines (EA14..EA19), as far as I know. Somebody else before you wanted to build a flash cartridge using the HuC1, see here, but I'm not sure what became of it.
You might get lucky though and find a 20th address line on pins 30 thru 32 (not sure, never tested it).
Happy hacking in any case 
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#3 2022-07-19 08:50:02
- Moex
- New member
- Registered: 2022-07-11
- Posts: 3
Re: Flashcard based on HUC1a using flash memory adapter
Hi Tauwasser,
thank you so much for your reply. Your scheme from the earlier thread helped me a lot!
I tried it and soldered on the adapter including the flashchip (AM29F016). Unfortunately, my flash software does not recognize any ROM on the cartridge. I am used to other PCB types that at least a cryptic ROM name shows up there and mapper, RAM size etc. are recognized. But here nothing happens.
I am using the GBxCart RW together with FlashGBX v3.15.
I connected the WR pin of the adapter to the 8th pin on the HUC1a.
After that I tried the untested pins (30, 31, 32) of the mapper. When I additionally soldered the 20th address line of the adapter to pin 32 of the HUC1a, a cryptic ROM name appeared in the flash software, but again the cartridge data is not recognized. As flashcard it is generally not recognized by the software, no matter whether with or without the soldered 20th address.
Did I perhaps overlook something important?
Last edited by Moex (2022-07-19 12:09:24)
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